Brake maintenance for a collector car

Question:

Nine years ago I bought a nice 1947 Pontiac. I pulled the wheels to inspect the drums, seals and bearings, peeled back the rubber boots and determined that the previous owner recently had a complete brake job done, so I have not worried about it since, and it has been fine.

Many of us service our own brakes. We change linings, have rotors or drums turned, and rebuild or replace wheel and master cylinders.

Daily driver cars usually get enough miles on them to let us know when something is wrong by the way they sound or feel. But collector cars are different. Because they are driven only lightly, the braking system can deteriorate with time rather than miles. When should we inspect the system to ward off catastrophic failure?

Answer:

I would inspect the brake system every time you service the car. And assuming you have conventional DOT 3 or DOT 4 brake fluid in your car, you should have the system purged every two years to get rid of moisture that accumulates in the lines. Regular brake fluid is hygroscopic, which means it absorbs moisture, and that will settle in your brake lines and corrode them. It will also become a danger because the boiling point of water is much lower than that of brake fluid and can boil and become steam and cause brake failure under hard braking.

Potential problems can actually be worse for cars that are left stationary for long periods of time. To begin with, if the emergency brake is left on, rear brake linings can bond to the drums to the point where the drums may have to be damaged to get them off. Rubber seals can also dry out, and moisture can settle in low spots in the system and rust out the tubing, causing the burst point of the tubing to be lowered.

One approach that I have found to be well worth the trouble and expense is switching to DOT 5 silicone brake fluid. This is not recommended for later systems with anti-lock brakes, but for classics from the ’60s on back it will largely end your brake failure problems. The stuff was invented for the postal service and is a bit more expensive than regular fluid, but in my experience it is well worth it. I have it in a 1940 Packard that I restored in 1983, and the system is still working well.

The only catch is you need to completely purge the system of the old fluid for it to be 100 percent effective. That is not because the fluids are incompatible, but because the residue of the old fluid will still attract water. I didn’t have to worry about that in my Packard because I completely replaced the hydraulic system and the linings. The only components I kept were the drums and the master cylinder. Since then I have only had to top up and adjust the system, and the brakes have worked just fine.

I did have the master cylinder sleeved with stainless steel though, because it was pitted and the stainless steel sleeve is nearly impervious.